Researchers probe net's most blighted darknet

150 Mbps of sustained garbage

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Researchers probing a previously unused swath of internet addresses say they've stumbled onto the net's most blighted neighborhoods, with at least four times as much pollution as any they've ever seen.

The huge chuck of more than 16.7 million addresses had never before been allocated and yet the so-called darknet was the dumping ground sustained barrages of misdirected data as high as 150 Mbps, with a peak as high as 870 Mbps, said Manish Karir, director of research and development at the non-profit group Merit Network. That was about four times higher than most darknets and 20 times higher than a previously unallocated address block of addresses set up as a control group.

The block is referred to as a 1/8 (pronounced one slash eight) or 1.0.0.0/8 because it comprises 1.0.0.0 through 1.255.255.255, a designation of 224 individual IP addresses. Almost as soon as it was allocated by IANA, or the Internet Assigned Numbers Authority, in late January, the researchers noticed it was absorbing huge amounts of garbage traffic, making many of the addresses largely unusable.

“It's basically like an unallocated plot of land and you don't know what's there because nobody has paid attention to it before,” Karir told The Register. “The concept of pollution is the same whether you're looking at a plot of land or whether you're looking at address space. And in both cases, it limits or it impacts the person who actually buys or owns that plot of land.”

Karir, who presented his findings at a meeting this week of the North American Network Operators' Group in San Francisco, said what seemed to make the 1/8 such a magnet for junk traffic was the concentration of addresses such as 1.1.1.1, which are easy for network administrators, end users and internet criminals to type. They enter the addresses into applications they are testing or configuring and never bother to think of the consequences for those on the receiving end.

Indeed, the most common forms of junk received on 1/8 were packets sent mostly to 1.1.1.1 using the RTP, or real-time transport protocol. Using the Wireshark application to inspect the data, the researchers discovered they were automatic recordings that telephone networks play when a caller reaches a disconnected or nonexistent number. Karir speculated they are the result of voice-over-internet-protocol servers that were configured to send data to the wrong address. The audio traffic comprised more than 34 percent of the packets received, and more than 50 percent of all bytes received.

Other types of junk traffic included system logs that were sent by misconfigured servers and packets sent by BitTorrent applications, DSL modems and experimental programs. Other IP addresses that were particularly hard hit were 1.1.168.192, 1.0.168.192 and 1.2.168.192, which appear to be the result of applications trying to connect to 192.168.1.1 and other common IP addresses reserved for local area networking.

Polluted darkspace is likely to pose more of a problem in the future because the number of unallocated IP addresses is quickly dwindling. In the days when the addresses were plentiful, network operators could simply return polluted blocks in exchange for ones that were clean. The adoption of the next-generated internet protocol, dubbed IPv6, will alleviate the shortage, but with the transition moving at a snail's pace, operators will have to grapple with polluted darknets for years. In the meantime, operators will have to find ways to clean up the blocks they are given, Karir said.

“When we get close to where there's no more additional space available, you will have to use what you're given,” he said.

But he said it won't be easy to cleaning up the dilapidated spaces. PDFs of the findings and possible solutions are here and here. Other organizations that participated in the research were APNIC and the University of Michigan. ®